1. Field
The present invention relates to a wireless communication system, and more specifically to a technology of controlling power for uplink transmission in a CoMP (Coordinated Multi-Point).
2. Discussion of the Background
Recently, MIMO (Multi-Input Multi-Output) systems are used to transmit high-speed, high-capacity data so as to raise transmission efficiency. Together with this, MIMO-based CoMP technologies are under discussion.
CoMP is directed to technologies of adjusting or combining signals transmitted from multiple points, and CoMP may have applications to increase data rate as well as to obtain high quality and high throughput.
As CoMP-supportive terminals, user equipment to which CoMP applies in a CoMP environment (hereinafter, a CoMP-supportive or CoMP-applicable system is referred to as ‘CoMP environment’ for convenience of description)? such user equipment is hereinafter referred to as ‘user equipment operating in a CoMP mode) aim to simultaneously receive data from a CoMP cooperated set or with the interference minimized in the CoMP cooperated set in consideration of the channel environment in each of cells constituting the CoMP cooperated set, so it need measure the channel information regarding each cell and report it to a serving cell of a corresponding user equipment.
The CoMP cooperated set refers to a set of points that directly or indirectly participate in (geographically away from) data transmission in any time-frequency resource for one UE (User Equipment). Here, “directly participate in data transmission” means that the points actually transmit data to UE in the corresponding time-frequency resource, and “indirectly participate in data transmission” means that the points do not actually transmit data in the corresponding time-frequency resource but contribute to making determinations on user scheduling/beamforming.
Meanwhile, it is required to define reference information, e.g., reference signal, to generate channel information in the CoMP cooperated set consisting of various cells and to share the information between the user equipment and base station.